Article View: comp.sys.super
Article #30Inner product / AXPY performance
From: Victor Eijkhout
Date: Thu, 30 Jul 1992 19:52
Date: Thu, 30 Jul 1992 19:52
23 lines
1158 bytes
1158 bytes
Yo hardcore number crunchers!
I would like to get an idea of the difference in performance
between inner products
do i=1,n x = x + a(i)*b(i)
and axpy operations
do i=1,n x(i) = x(i) + a*b(i)
which both have the same number of operations, but the inner product
has an accumulation, which traditionally seems to be an
unvectorizable idea.
Please post if you know how your favourite vector processor / vector
chip / Risc processor / whatever performs differently / the same
on the two.
My guess would be that the difference between these two operations
can nowadays be conveniently neglected, but I might be wrong.
Victor.
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Path: arc1-ca.pugleaf.net!sparky!uunet!usc!sol.ctr.columbia.edu!emory!utkcs2!cupid.cs.utk.edu!eijkhout From: eijkhout@cupid.cs.utk.edu (Victor Eijkhout) Newsgroups: comp.sys.super,comp.lang.fortran Subject: Inner product / AXPY performance Message-ID: <l7gi3fINNmsd@utkcs2.cs.utk.edu> Date: 30 Jul 92 19:52:15 GMT Reply-To: eijkhout@cupid.cs.utk.edu (Victor Eijkhout) Organization: University of Tennessee, Knoxville - Department of Computer Science Lines: 23 NNTP-Posting-Host: cupid.cs.utk.edu